Process of casting iron screen-plates for steel grids



D. BROWN.

PROCESS OF CASTING IRON SCREEN PLATES FOR STEEL GRIDS.

' APPLICATION FILED DEC. 14. 1917.

Patented May 4, 1920.

2 SHEETS-SHEET I.

ftverli' 0 7 ,Davis flrowv-a D. BROWN. PROCESS OF CASTING IRON SCREENPLATES FOR STEEL GRIDS.

APPLIC A TION FILED DEC 14. I917- Patented May 4, 1920.

2 SHEETS-SHEET 2- DAVIS BROWN, or BUCYBUS, onr ns'sren-on TOTHEAMnnIcAn'oLAY MACHINERY GOM PANY, A CORPORATION OF OHIO. v

PROCESS CASTING IRON SCREEN-PLATES STEEL GRIDS Specification of LettersPatent.

Patented. May 4, 1920.

Application filed December 14, 1917. Serial- 110. 207,043.

To all whom it may concern.

Be it known that .I, DAVIS BROWN, a citizen of the United States, andresident of Bucyrus, in the county of Crawford and State of Ohio, haveinvented an Improvement in Processes of Casting Iron Screen- Plates forSteel Grids, of which the following description, in connection withptheaccompanying drawings, is a specification, l ke letters on the drawingsrepresenting l1ke parts.

My present invention is an improved dry pan, for use in pulverizing andgrinding clay and similar substances, and the lnvention moreparticularly relates to an 1mproved construction of screen platestherefor, and to a novel method of maklng the same.

974,818, issued November 8, 1910, where an efficient type of this kindof machlne is shown, the screen plates utilized have been in crosssection and producing an exceedingly large surface area of the cast 1r0nin proportion to the slots through which the ground material isscreened. These bars or grids, when made of cast iron,'must also berelatively short in length'to avoid liability of breakage.

expense and labor involved have been so great that this also has beenobjectionable. The use of such steel grids, heretofore, has

required the fitting in the rolled steel grids,

in a cast iron framework, but. because of the difliculty, time andprohibitive cost, this method has never been commercially practicable. l

My present invention enables a screen to be made of steel bars in aneconomical and practicable manner, and by a novel process ofmanufacture, whereby t e diflicultles and In dry pans, such for example.as. that shown in the patent to R. G. Penfield, No.

Attempts have been made to utilize steel grids or bars, but the expenseheretofore met with are entirely eliminated. In carrying out my presentinventionI provide the usual. pattern for easting the frame of thescreen around the outer side,'but I so arrange an intermediate sectionfor supporting the'inner ends of the grids as to form same first inrelatively thin metal portions capable of springing during the coolingof the'frame' without danger of distorting the heavier outside rims. Iaccomplish this by first forming'the middle section or partition in ausual manner and then fitting a core through the middle section of'themold for'this middle partition, applying the steel bars throughout themold in desired proximity with their outer ends in line to fit withinthe casting and the inner ends. within one of the relatively thin middlepartitions cast by the application of the core through the middle moldas above explained.v The iron is then'cast to form the frame,firmlyengaging and holding the respective ends of the steel rids,'andperpermitted to cool. During t is cooling, the contraction of the framemay draw the inner thin partitions somewhat, but said innerpartitions'are'so formed as to spring and permit this contraction.Thereafter the middle section is again fittedin a mold, and the spacefrom which the core has been removed isfil'led 111 p with molten iron,as a separate casting. referably the second casting is made to dovetailwith or interlock about the two thin members which were originally madefor the central partitions. This process thusrproduces an improvedscreen, with an iron frame and steel grids or bars, permitting the sameto be made in a feasible, practicable and commercialimanner at a minimumof cost, automatically taking care of the normal tendency of the metalto shrink or contract when cooling down in a mold, and furthermorepreventing the steel bars from buckling when cooling. I believe thatthis process is a distinct novelty in the art, and therefore wish toclaim the same broadly.

- Referringto the drawings illustrating a preferred embodiment of theinvention,

Fig. 1 is a view partly in cross section of a dry pan; 1

Fig. 2 is an enlarged view of one of the screen plates;

Fig. 3 is a cross-sectional view on the line 33 of Fig. 2;

Figs. 4 and 5 .and 6 are detailed views of the connections between thesteel grid bars and the cast iron frame.

I have shown in the drawings, for illustrative purposes, the type of drypan such as that illustrated in Patent 9%,818, above referred to,wherein the dry pan is built upon the foundation or framework 1, hav ingsuitable side frames 2, a central drive shaft 3, suitable mechanism forsupporting the mullers 4, the main grinding base or hub 5, radialcarrying flanges (3, and cylindrical rim 7 carrying the screen plates 8,arranged in segmental sections around the revolving pan. y

Each screen section, as illustrated in Fig. 2, comprises a frame withthe inner rim portions 10 and outer rim portions 11 in concentric arcsand of a size suitable for the diameter of dry pan in which they are tobe employed. This section is further formed with radial frame portions12 and 13, built of cast iron. The radial frame portions 12 and 13 areeach formed as shown in Fig. 1 with a dove-tailed recess as indicated at1 1 to receive the correspondingly shaped end 15 of a steel grid bar 16.Preferably these recesses 14 are made in groups of three or four, foursuch being shown at 17, 17, 17, 17, in the drawings. This permits a setof four grid bars of the same length to be interchangeably fitted atappropriate sections throughout the screen.

The dovetailing arrangement of the steel grid bars in the outer castiron frame sections 12 and 13 as just described, is readily accomplishedby fitting the bars therein be fore the central partition 20 is formed.As shown in Fig. 5, the inner ends of the steel bars 16 are similarlydovetailed and fitted into a thin spacing and carrying member 21 and 21,which members 21 are appropriately'spaced from each other to permit thesubsequent pouring of the iron to form the rest of the middle partition20. I prefer to formthese thin divisional walls of irregular shape, suchas, for example on the curved lines 22, 22, in order to provide aninterlock-- ing when the rest of this middle partition member, via, themember 20, is cast therein.

The pattern is molded in the sand in the usual way, then the pattern iswithdrawn and a dry sand core, substantially of the form shown at 20,Fig. 2, and the steel bars, 1.6,are placed'in the sand in their properplaces. The mold is then closed and the cast iron poured around the bars16 and the core in the place of the member 20. After cooling the castingis removed from the sand and cleaned. The core being cleaned out leavesa space between the two division walls 21. In cooling, the cast ironframe shrinks closing in on the bars and forces them to ward the centerand the center division walls 21, which being purposely lighter andweaker than the other and outer walls of the frame, will spring or maybebreak away from the main frame at the junction points and this is whatprevents buckling of the bars or weakening of the main frame when itcontracts in cooling. The space between the two light division walls 21permits them to spring toward or from each other and relieve the barsand the main frame of the strains caused by the shrinkage of the castframe on cooling down from the molten state. The bars are not sub-- jectto this shrinkage. After cooling down and cleaning, th frame is 'againplaced in the sand and the space between the two light center walls andadditional space below these light partition walls is poured filling thevacant space between them and forming a permanent support beneath them,interlocking, solidifying, and strengthening the center partition '20,21 and 21 being a substantially solid member. My novel process of thuscombining steel grid bars with the cast iron frame, also secures theadvantages of a simple and economical construction, and presents ascreen plate with the desired increase in area of openings and withsteel grids which. will outlast the cast iron many times over.

Fig. 6 illustrates, in cross section on the line 66 of Fig. 2, thepresent arrangement for the reinforcing poured metal 20 of themiddlepartition, where the same interlocks and bears upon the frame 10.

lVhile I have described my novel method of construction as for useprincipally in making screen plates with the outside frame of cast ironand the grid bars of steel, and while I wish to-claim the resultingscreen plates as a new article of manufacture, it will be appreciatedthat the method is not limited to the manufacture of screen'plates. Ibelieve that my novel method of manufacture, which consists in theprovision of relatively thin members, such as the partition members 21,capable of spring during contracting or cooling, is a distinct noveltyin the art wherein the problems incident to casting metals,especiallyusing different metals are present. I therefore wish to claim thismethod broadly, relying upon the illustration herein as a specificmanner of carrying out this method, without, however, limiting the sameto such screen plates.

hly invention is further described and defined in the form of claims asfollows:

1. The improved method of manufacturing articles from cast metal, whichconsists in forming a mold for the resulting casting, coring a portionof the. mold form, in a manner to leave an interlocking or dovetailedcontour, casting the metal therein, then allowing said metal to cool andcontract and then subsequently casting metal in the first'cored portion,and causing'the second casting of metal to interlock with thecooperating contour therefor of the first cored portion.

2. The improved method of casting an article having a cast iron outerframe and steel bars extending from one portion of said frame to theother, which consists in forming a mold, coring one portion of the mold,applying the bars from one frame section to said cored portion, castingthe iron therein, allowing the casting to cool and contract, said coredsection being relatively thin, to spring or yield during cooling,whereby the main portion of the frame will be relieved from shrinkingstrains during said cooling.

3. The improved method of casting an article having a cast iron outerframe and steel bars extending from one portion of said frame to theother, which consists in forming a mold, coring one portion of the mold,applying the bars from one frame section to said cored portion, castingthe iron therein, allowing the casting to cool and contract, said coredsection being relatively thin, to spring or yield during cooling, andthen casting a strengthening member adjacent the cored portion of theframe.

4%.. The improved method of casting an iron screen plate with steel gridbars having a central partition to receive the inner ends of said bars,which consists in forming a mold, placing the steel bars in the moldwith their outer ends in position in the frame mold, and their innerends respectively in a relatively narrow portion of the inner mold,coring said inner frame mold between the ends of the grid bars, castingthe frame, then permitting said frame to cool, and then casting areinforcing member for the middle partition substantially in place ofthe originally cored portion.

5. The improved method of casting an iron screen plate with steel gridbars having a central partition to receive the inner ends of said bars,which consists in forming a mold, placing the steel bars in the moldwith their outer ends in position in the frame mold, and their innerends respec tively in a relatively narrow portion of the inner mold,coring said inner frame mold between the ends of the grid bars, castingthe frame, then permitting said frame to cool, and then casting areinforcing member having an interhicking contour with said middlepartition substantially in place of the originally cored portion.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

DAVIS BROlVN'.

lVitnesses H. L. TIARMON, A. B. BRADSTOOK.

